145 research outputs found
An optimised system for generating multi-resolution DTMS using NASA DTMS datasets
Abstract. Within the EU FP-7 iMars project, a fully automated multi-resolution DTM processing chain, called Co-registration ASP-Gotcha Optimised (CASP-GO) has been developed, based on the open source NASA Ames Stereo Pipeline (ASP). CASP-GO includes tiepoint based multi-resolution image co-registration and an adaptive least squares correlation-based sub-pixel refinement method called Gotcha. The implemented system guarantees global geo-referencing compliance with respect to HRSC (and thence to MOLA), provides refined stereo matching completeness and accuracy based on the ASP normalised cross-correlation. We summarise issues discovered from experimenting with the use of the open-source ASP DTM processing chain and introduce our new working solutions. These issues include global co-registration accuracy, de-noising, dealing with failure in matching, matching confidence estimation, outlier definition and rejection scheme, various DTM artefacts, uncertainty estimation, and quality-efficiency trade-offs
Massive stereo-based DTM production for Mars on cloud computers
Digital Terrain Model (DTM) creation is essential to improving our understanding of the formation processes of the Martian surface. Although there have been previous demonstrations of open-source or commercial planetary 3D reconstruction software, planetary scientists are still struggling with creating good quality DTMs that meet their science needs, especially when there is a requirement to produce a large number of high quality DTMs using "free" software. In this paper, we describe a new open source system to overcome many of these obstacles by demonstrating results in the context of issues found from experience with several planetary DTM pipelines. We introduce a new fully automated multi-resolution DTM processing chain for NASA Mars Reconnaissance Orbiter (MRO) Context Camera (CTX) and High Resolution Imaging Science Experiment (HiRISE) stereo processing, called the Co-registration Ames Stereo Pipeline (ASP) Gotcha Optimised (CASP-GO), based on the open source NASA ASP. CASP-GO employs tie-point based multi-resolution image co-registration, and Gotcha sub-pixel refinement and densification. CASP-GO pipeline is used to produce planet-wide CTX and HiRISE DTMs that guarantee global geo-referencing compliance with respect to High Resolution Stereo Colour imaging (HRSC), and thence to the Mars Orbiter Laser Altimeter (MOLA); providing refined stereo matching completeness and accuracy. All software and good quality products introduced in this paper are being made open-source to the planetary science community through collaboration with NASA Ames, United States Geological Survey (USGS) and the Jet Propulsion Laboratory (JPL), Advanced Multi-Mission Operations System (AMMOS) Planetary Data System (PDS) Pipeline Service (APPS-PDS4), as well as browseable and visualisable through the iMars web based Geographic Information System (webGIS) system
Enhancement Of Stereo Imagery By Artificial Texture Projection Generated Using A Lidar
Passive stereo imaging is capable of producing dense 3D data, but image matching algorithms generally perform poorly on images
with large regions of homogenous texture due to ambiguous match costs. Stereo systems can be augmented with an additional light
source that can project some form of unique texture onto surfaces in the scene. Methods include structured light, laser projection
through diffractive optical elements, data projectors and laser speckle. Pattern projection using lasers has the advantage of producing
images with a high signal to noise ratio. We have investigated the use of a scanning visible-beam LIDAR to simultaneously provide
enhanced texture within the scene and to provide additional opportunities for data fusion in unmatched regions. The use of a LIDAR
rather than a laser alone allows us to generate highly accurate ground truth data sets by scanning the scene at high resolution. This is
necessary for evaluating different pattern projection schemes. Results from LIDAR generated random dots are presented and
compared to other texture projection techniques. Finally, we investigate the use of image texture analysis to intelligently project
texture where it is required while exploiting the texture available in the ambient light image
An update on the development of ASPIRED
We are reporting the updates in version 0.2.0 of the Automated SpectroPhotometric REDuction (ASPIRED) pipeline, designed for common use on different instruments. The default settings support many typical long-slit spectrometer configurations, whilst it also offers a flexible set of functions for users to refine and tailor-make their automated pipelines to an instrument's individual characteristics. Such automation provides near real-time data reduction to allow adaptive observing strategies, which is particularly important in the Time Domain Astronomy. Over the course of last year, significant improvement was made in the internal data handling as well as data I/O, accuracy and repeatability in the wavelength calibration
Crack detection in "as-cast" steel using laser triangulation and machine learning
We describe a high-accuracy inspection system designed to automatically detect cracks in "as-cast" steel slabs. Real-time slab inspection requires instrumentation capable of withstanding high temperatures above the steel surface as well as coping with the dirty and dusty environment present in a steel mill. Crack detection is also challenging due to the presence of oxidation scale on the slab surface. A bespoke laser triangulation system has been developed, providing images at 250 fps with a calibrated surface resolution of 97 ÎŒm from a 1m standoff distance. Cracks are detected using a combination of morphological detection and SVM classifier. Results are reported from laboratory testing and from extended trials at a production steel mill
Requirements and Limitations of Thermal Drones for Effective Search and Rescue in Marine and Coastal Areas
Search and rescue (SAR) is a vital line of defense against unnecessary loss of life. However, in a potentially hazardous environment, it is important to balance the risks associated with SAR action. Drones have the potential to help with the efficiency, success rate and safety of SAR operations as they can cover large or hard to access areas quickly. The addition of thermal cameras to the drones provides the potential for automated and reliable detection of people in need of rescue. We performed a pilot study with a thermal-equipped drone for SAR applications in Morecambe Bay. In a variety of realistic SAR scenarios, we found that we could detect humans who would be in need of rescue, both by the naked eye and by a simple automated method. We explore the current advantages and limitations of thermal drone systems, and outline the future path to a useful system for deployment in real-life SAR
The WAGGS project -- III. Discrepant mass-to-light ratios of Galactic globular clusters at high metallicity
Observed mass-to-light ratios (M/L) of metal-rich globular clusters (GCs) disagree with theoretical predictions. This discrepancy is of fundamental importance since stellar population models provide the stellar masses that underpin most of extragalactic astronomy, near and far. We have derived radial velocities for 1,622 stars located in the centres of 59 Milky Way GCs - twelve of which have no previous kinematic information - using integral-field unit data from the WAGGS project. Using N-body models, we then determine dynamical masses and M/L ratios for the studied clusters. Our sample includes NGC 6528 and NGC 6553, which extend the metallicity range of GCs with measured M/L up to [Fe/H] ~ -0.1 dex. We find that metal-rich clusters have M/L more than two times lower than what is predicted by simple stellar population models. This confirms that the discrepant M/L-[Fe/H] relation remains a serious concern. We explore how our findings relate to previous observations, and the potential causes for the divergence, which we conclude is most likely due to dynamical effects
The WAGGS project-III. Discrepant mass-to-light ratios of Galactic globular clusters at high metallicity
Observed mass-to-light ratios (M/L) of metal-rich globular clusters (GCs) disagree with theoretical predictions. This discrepancy is of fundamental importance since stellar population
models provide the stellar masses that underpin most of extragalactic astronomy, near and far. We have derived radial velocities for 1622 stars located in the centres of 59 Milky Way GCs 12 of which have no previous kinematic information - using integral-field unit data from the WAGGS project. Using N-body models, we determine dynamical masses and M/LV for the
studied clusters. Our sample includes NGC 6528 and NGC 6553, which extend the metallicity range of GCs with measured M/Lup to [Fe/H] ⌠â0.1 dex. We find that metal-rich clusters have M/LV more than two times lower than what is predicted by simple stellar population models. This confirms that the discrepant M/L-[Fe/H] relation remains a serious concern. We explore how our findings relate to previous observations, and the potential causes for the divergence, which we conclude is most likely due to dynamical effects
First Search for Unstable Sterile Neutrinos with the IceCube Neutrino Observatory
We present a search for an unstable sterile neutrino by looking for a
matter-induced signal in eight years of atmospheric data collected
from 2011 to 2019 at the IceCube Neutrino Observatory. Both the (stable)
three-neutrino and the 3+1 sterile neutrino models are disfavored relative to
the unstable sterile neutrino model, though with -values of 2.5\% and
0.81\%, respectively, we do not observe evidence for 3+1 neutrinos with
neutrino decay. The best-fit parameters for the sterile neutrino with decay
model from this study are ,
, and , where
is the decay-mediating coupling. The preferred regions from short-baseline
oscillation searches are excluded at 90\% C.L
- âŠ